Monday, 27 March 2017

New rarity coding system for Ontario birds

Some of you may recall that back in 2012 when I embarked on my Ontario Big Year of birding, I went ahead and categorized every species on the Ontario checklist into one of six codes demonstrating their relative scarcity in the province. My reasoning was simple - it was a good way to objectively observe how well I was progressing on my Big Year, based on how many species I had seen that were considered genuine rarities.

Code 2: Localized species that require additional effort, but each can be seen without too much difficulty in Ontario each year (Louisiana Waterthrush, Orange-crowned Warbler, Tufted Titmouse, King Eider, Grasshopper Sparrow, Common Gallinule, Golden Eagle)

Code 4: Genuine rarities, however rarities that are more or less expected and show up pretty much every year (Western Grebe, Black-necked Stilt, White-winged Dove, Kirtland's Warbler, Spotted Towhee). Some of the rarest breeding birds in Ontario also are Code 4 species (Barn Owl, Northern Bobwhite, Henslow's Sparrow).

Code 5: Big time rarities that show at least some kind of pattern of vagrancy in Ontario (Black-bellied Whistling-Duck, Purple Gallinule, Dovekie, Lewis's Woodpecker, Rock Wren). Several chase-able species are reported each year in the province, and over the course of a lifetime an ambitious birder should be able to chase nearly every individual on this list. However, even Ontario's top listers are each missing a handful of species from this list.

Code 6: the rarest of the rare, the genuine mega rarities that we have on our provincial list (Roseate Spoonbill, Inca Dove, Little Stint, Broad-billed Hummingbird, Plumbeous Vireo). Anything with more than three records did not make the cut!

Little Egret (Code 6)

In the time since coming up with the coding system, I have decided to tweak the codes for some of the species for a variety of reasons. Below, I will list each species in which I have changed their codes, with their former code listed in brackets.

The issue with an analysis like this is that the relative rarity of each species in Ontario forms a continuum; they do not all fit into six neat little boxes. In other words, there will be little difference between a "tough Code 3" and an "easy Code 4". For example, I have Townsend's Solitaire as a Code 4 and Varied Thrush as Code 3, but one could easily argue that they should both be the same category. What about Ash-throated Flycatcher, which historically has been a Code 5? There have now been five records in the last four years in Ontario and it is a species reported more and more to the northeast States in recent years. I have left it as a Code 5 for now, but in the next few years it may be appropriate to re-categorize it as a Code 4. How about Carolina Wren and Nothern Mockingbird? I have them listed as Code 1, but should it join species like Tufted Titmouse, Marsh Wren, Boreal Chickadee, etc as a Code 2?

Tufted Titmouse (Code 2)

Clearly, the status of many of these species, in particular the rare ones, can change from year to year. Some years Cave Swallow could be treated as a Code 2, while in other years they are completely absent in the province. Common Redpoll can be abundant throughout the province some winters, yet other winters it can be quite difficult.

Cave Swallow (Code 3)

Most of the changes that I made had to do with my analysis of how common each species is. That being said, there are a handful of species whose status in Ontario has changed quite a bit in the five years since I came up with the coding system. Several species have become much more regular in recent years, and that is reflected in their new codes. These include Neotropic Cormorant, Fish Crow and Black Vulture, while Eurasian Collared-Dove was on the cusp and has been left as a Code 4 for now. Ross's Goose and Greater White-fronted Goose also appear to have increased in recent years, but for now I left them as Code 3. An argument could definitely be made that they should fit in the Code 2 category, however!

Fish Crow (Code 3)

This coding system is clearly southern Ontario-centric. In reality, quite a few of the Code 1 species would be quite difficult for a Thunder Bay birder who does not venture south. That being said, if someone was attempting a big year in Ontario, all of the Code 1 species would be easy since that individual would certainly spend sufficient time in southern Ontario. On the flip side, some of the species I have listed as Code 3 would be somewhat easy for a northwestern Ontario birder, such as Black-billed Magpie, some of the difficult boreal birds, Harris's Sparrow, etc.

Harris's Sparrow (Code 3)

I made an effort to trim down the species labelled as Code 1, reserving that code for the genuinely easy birds that are guaranteed to most birders in a year; in particular, fairly widespread species. Some of these former Code 1 species are guaranteed for birders in certain parts of the province, but may be more difficult for quite a few other birders. Some examples include Ring-necked Pheasant, Marsh Wren and Northern Saw-whet Owl.

I changed the codes of some highly localized species from Code 2 to Code 3, including Black-billed Magpie, Yellow-headed Blackbird and Barrow's Goldeneye.

Yellow-headed Blackbird (Code 3)

Code 6 species should be the rarest of the rare, with a maximum of three provincial records. Mostly, these are one-off species though a bunch have two or three provincial records. Therefore I have moved quite a few species to Code 5, including Anhinga, Least Tern, Wilson's Plover, Common Ground-Dove and Gray Flycatcher. Some of these species were moved off of Code 6 in part because of recent records for the province (Prairie Falcon, Crested Caracara, Cassin's Kingbird, etc). Note that many of the new Code 6 species are new additions to the provincial list, so they were not included in the original coding system.

Wilson's Plover (Code 5)

I am not sure why I had Whooping Crane listed as Code 5, as there has not actually been an OBRC-accepted record since the OBRC's inception. The problem is that the birds occasionally seen in Ontario cannot be determined to be from the "natural" population. There is an introduced population in Wisconsin. Perhaps eventually those birds will be countable in Ontario, but for now its practically impossible to have an accepted record of Whooping Crane for the province.

I was not sure how to treat Hurricane birds. For instance, Black-capped Petrel has 26 accepted records for the province, though the vast majority of these birds arrived during a single hurricane in 1996. Twenty-six records is usually grounds for a species to be a Code 4, but I have moved it to Code 5 as suitable hurricanes are exceedingly rare; in fact there have only been three or four of these hurricanes in the last century. Leach's Storm-Petrel was formerly a Code 6, but I have changed it to Code 5 since it also has a history of showing up with hurricanes.

Two species that breed in Ontario are essentially limited to the Hudson Bay coast - Smith's Longspur and Willow Ptarmigan - with only a couple of records further south in the province. It is difficult for your average birder to make it to the northern coast to see these species; I have not managed to get up there yet. However I think these species should be treated as Code 3 species along with the other localized birds in Ontario.

Smith's Longspur (Code 3)

That is all for now. If anyone has any comments on what you think I should change, feel free to send me an email (joshvandermeulen(at)live.ca) or comment on this post - the coding system is by no means set in stone!

1 comment:

Thanks Josh for making this available. It has been an object of desire for a while now. Know your work is appreciated. We've recently moved from Cochrane down to the Hamilton area, putting more of these birds in reach.